The Bureau of Standards experimental radio station, WWV, was first set up in 1919.
 
Scientific American, May 22, 1920, page 571:

The  Portaphone--A  Wireless  Set  for  Dance  Music  or  the  Day's  News
exterior portaphone viewinterior portaphone view THOSE who have not kept pace with the developments in radio communication are apt to think of the wireless telegraph or telephone as a complicated arrangement of delicate apparatus, involving also aerial wires and an array of various devices formidable and involved in appearance. They would be surprised indeed to learn that a receiving instrument--the Portaphone--has been developed in the Radio Section of the United States Bureau of Standards at Washington, which, packed in an ordinary case, can be transported with much less difficulty than a simple talking machine, and which may be placed anywhere and receive wireless impulses in the form of signals, music or speech, reproducing the same through a loud-speaking telephone and horn as shown in the illustrations below.
    It will appear from the scale placed alongside of the portaphone, that its height is some 12 inches exclusive of the horn, while the compactness of the apparatus is shown in the view representing its interior. This device, furthermore, does not require an expert operator, but may be arranged by any one without previous special knowledge or training.
    The portaphone opens up many new possibilities. For instance, at 8:30 o'clock each evening a central station might send out dance music from its transmitting apparatus and those who cared to dance could set up their portaphones on a table, turn on the current and have the music furnished sufficiently loud to fill a small room. Or in the morning a summary of the day's news might be sent out to he received by a portaphone and digested by a family at breakfast, in which all could participate whether paterfamilias had the paper or not.
    Obviously there are a number of other applications of this simple device which serves to reproduce sound from the waves sent through space. A glance at the apparatus shows its simplicity. On the inside of the door of the case is shown a rectangle of wire forming the radio compass, direction coil, or "loops," which takes the place of the usual elevated aerial or antenna. The capacity can be adjusted so as to tune the apparatus to the required wave length. The receiving set makes use of a vacuum tube detector and a two-stage amplifier, all operated by dry cells. The signals are passed on to a special loud-speaking telephone to make the vibrations audible, while the large horn reinforces the sound waves until they completely fill a small room.
    The instrument as constructed at present has a range of about 15 miles, or well within the limits of an ordinary city. The impulses sent out can be of such a wave length as not to interfere with commercial wireless. The instrument is not sufficiently sensitive to respond to the ordinary long-distance signals coming from Government or marine or commercial stations. So far the only application of the portaphone has been purely experimental at the Bureau of Standards, but it presents interesting possibilities for more general and utilitarian applications. A similar device with a larger coil has been built there in the Radio Section, which develops sufficient power in connection with a transmission source to reproduce music loud enough to fill a very large room suitable for dancing.--By Herbert T. Wade.